What do I do about an almost 3 year old picky eater whos' been that way since he was14months old?

My son will eat pizza, Raviolis, rice, beans and some soups, but that is it. He will not eat vegetables nor will he try anything new ever. We try, but to no avail. He does eat yogurt and loves milk so he's getting calcium, but I worry about other nutrients he is not getting. He weighs 33lbs. I think that is okay. He is not malnurished, but it just worries me. Any ideas?